1. Field of the Invention
The present invention relates to a patterned thin film including a linear portion and a method of forming the same.
2. Description of the Related Art
Frame plating is one of the methods of forming a thin film that is patterned (referred to as patterned thin film in the present patent application), such as the method disclosed in Published Examined Japanese Patent Application Showa 56-36706 (1981). To perform the frame plating disclosed, an electrode film is formed on a substrate, for example, and a resist layer is formed on the electrode film. The resist layer is patterned by photolithography to form a frame to be used for plating. Electroplating is then performed through the use of the frame with the electrode film already formed as an electrode and a seed layer, so as to form a patterned thin film made of a conductive material.
A patterned thin film formed by frame plating may be utilized in microdevices, for example. Such microdevices include a thin-film inductor, a thin-film magnetic head, a semiconductor device, a sensor incorporating thin films, and an actuator incorporating thin films.
Patterned thin films include those having a plurality of linear portions disposed side by side, such as a coil or wiring. For such a patterned thin film it is required to reduce the width of the linear portions and to reduce the space between adjacent linear portions in some cases so as to enhance the integration.
If the width of the linear portions of the patterned thin film is made too small, however, the resistance of the linear portions increases and a problem such as generation of heat in the linear portions arises.
The following problem arises if the space between adjacent ones of the linear portions of the patterned thin film is reduced. When the patterned thin film is formed by frame plating, the space between adjacent ones of the linear portions is determined by the width of a dividing portion disposed between adjacent ones of grooves of the frame. The minimum width of the dividing portion depends on the resolution of the resist used for making the frame. The resolution of the resist is determined by the material of the resist and the exposure method. As thus described, to form the patterned thin film by frame plating, it is difficult to make the space between adjacent ones of the linear portions of the patterned thin film smaller than the limit determined by the resolution of the resist.